The present invention relates generally to imaging spectrometer devices, and in particular to a slewing narrow-angle imaging zoom for a wide field-of-view imaging spectrometer (WFIS).
WFIS systems are useful for range of applications, and are particularly suited to high altitude hyperspectral imaging applications. As such, WFIS systems are most often found on airplanes, unmanned aerial vehicles (UAVs) and imaging satellites. Conventional WFIS systems are one-dimensional imagers with a single wide angle reception slit that receives light into a two-mirror Schwarzchild telescope. This Schwarzchild telescope is coupled to the flat entrance slit of an imaging spectrometer via aspheric mirrors. The imaging spectrometer produces a two-dimensional spectrographic projection of the one-dimensional Wide FOV telescope image, wherein one dimension corresponds to spatial/angular location, and another to wavelength. This projection is received by an imaging detector such as a charge coupled device (CCD) camera. Images captured by a WFIS system can be analyzed in real time, or stored for later analysis. Although WFIS systems may be constructed to operate only over the visual spectrum, many WFIS systems are hyperspectral imagers that also capture spectral information over infrared and/or ultraviolet spectra. Increased spectral range and resolution are both useful for differentiating between objects that appear similar across visible wavelengths, such as visually camouflaged objects. Specific applications may, for instance, require IR images, UV images, or images across a wide spectrum including IR, visible, and UV wavelengths. Hyperspectral imaging can facilitate highly accurate object and pattern recognition. For in-depth description of one WFIS system, see U.S. Pat. No. 5,768,040, entitled “Wide Field-of-View Imaging Spectrometer” and “Wide Field Imaging Spectrometer (WFIS)—Instrumental Design and First Field Tests” (H. R. Pollock et al.), Lunar and Planetary Science XXXVI (2005).
Conventional WFIS systems can gather staggeringly large quantities of spectral data. In some applications, these quantities can exceed onboard storage and/or transmission capacities, resulting in the loss of valuable imaging data.